diff options
| -rw-r--r-- | include/linux/uio.h | 7 | ||||
| -rw-r--r-- | lib/iov_iter.c | 55 |
2 files changed, 55 insertions, 7 deletions
diff --git a/include/linux/uio.h b/include/linux/uio.h index 3d8f1acc142c..55ce99ddb912 100644 --- a/include/linux/uio.h +++ b/include/linux/uio.h @@ -26,6 +26,7 @@ enum iter_type { ITER_KVEC = 2, ITER_BVEC = 4, ITER_PIPE = 8, + ITER_DISCARD = 16, }; struct iov_iter { @@ -72,6 +73,11 @@ static inline bool iov_iter_is_pipe(const struct iov_iter *i) return iov_iter_type(i) == ITER_PIPE; } +static inline bool iov_iter_is_discard(const struct iov_iter *i) +{ + return iov_iter_type(i) == ITER_DISCARD; +} + static inline unsigned char iov_iter_rw(const struct iov_iter *i) { return i->type & (READ | WRITE); @@ -220,6 +226,7 @@ void iov_iter_bvec(struct iov_iter *i, unsigned int direction, const struct bio_ unsigned long nr_segs, size_t count); void iov_iter_pipe(struct iov_iter *i, unsigned int direction, struct pipe_inode_info *pipe, size_t count); +void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count); ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages, size_t maxsize, unsigned maxpages, size_t *start); ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages, diff --git a/lib/iov_iter.c b/lib/iov_iter.c index c42b928b15ef..7ebccb5c1637 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -83,6 +83,7 @@ const struct kvec *kvec; \ struct kvec v; \ iterate_kvec(i, n, v, kvec, skip, (K)) \ + } else if (unlikely(i->type & ITER_DISCARD)) { \ } else { \ const struct iovec *iov; \ struct iovec v; \ @@ -114,6 +115,8 @@ } \ i->nr_segs -= kvec - i->kvec; \ i->kvec = kvec; \ + } else if (unlikely(i->type & ITER_DISCARD)) { \ + skip += n; \ } else { \ const struct iovec *iov; \ struct iovec v; \ @@ -838,7 +841,9 @@ size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, size_t wanted = copy_to_iter(kaddr + offset, bytes, i); kunmap_atomic(kaddr); return wanted; - } else if (likely(!iov_iter_is_pipe(i))) + } else if (unlikely(iov_iter_is_discard(i))) + return bytes; + else if (likely(!iov_iter_is_pipe(i))) return copy_page_to_iter_iovec(page, offset, bytes, i); else return copy_page_to_iter_pipe(page, offset, bytes, i); @@ -850,7 +855,7 @@ size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes, { if (unlikely(!page_copy_sane(page, offset, bytes))) return 0; - if (unlikely(iov_iter_is_pipe(i))) { + if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { WARN_ON(1); return 0; } @@ -910,7 +915,7 @@ size_t iov_iter_copy_from_user_atomic(struct page *page, kunmap_atomic(kaddr); return 0; } - if (unlikely(iov_iter_is_pipe(i))) { + if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { kunmap_atomic(kaddr); WARN_ON(1); return 0; @@ -978,6 +983,10 @@ void iov_iter_advance(struct iov_iter *i, size_t size) pipe_advance(i, size); return; } + if (unlikely(iov_iter_is_discard(i))) { + i->count -= size; + return; + } iterate_and_advance(i, size, v, 0, 0, 0) } EXPORT_SYMBOL(iov_iter_advance); @@ -1013,6 +1022,8 @@ void iov_iter_revert(struct iov_iter *i, size_t unroll) pipe_truncate(i); return; } + if (unlikely(iov_iter_is_discard(i))) + return; if (unroll <= i->iov_offset) { i->iov_offset -= unroll; return; @@ -1055,6 +1066,8 @@ size_t iov_iter_single_seg_count(const struct iov_iter *i) return i->count; // it is a silly place, anyway if (i->nr_segs == 1) return i->count; + if (unlikely(iov_iter_is_discard(i))) + return i->count; else if (iov_iter_is_bvec(i)) return min(i->count, i->bvec->bv_len - i->iov_offset); else @@ -1103,6 +1116,24 @@ void iov_iter_pipe(struct iov_iter *i, unsigned int direction, } EXPORT_SYMBOL(iov_iter_pipe); +/** + * iov_iter_discard - Initialise an I/O iterator that discards data + * @i: The iterator to initialise. + * @direction: The direction of the transfer. + * @count: The size of the I/O buffer in bytes. + * + * Set up an I/O iterator that just discards everything that's written to it. + * It's only available as a READ iterator. + */ +void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count) +{ + BUG_ON(direction != READ); + i->type = ITER_DISCARD | READ; + i->count = count; + i->iov_offset = 0; +} +EXPORT_SYMBOL(iov_iter_discard); + unsigned long iov_iter_alignment(const struct iov_iter *i) { unsigned long res = 0; @@ -1127,7 +1158,7 @@ unsigned long iov_iter_gap_alignment(const struct iov_iter *i) unsigned long res = 0; size_t size = i->count; - if (unlikely(iov_iter_is_pipe(i))) { + if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { WARN_ON(1); return ~0U; } @@ -1197,6 +1228,9 @@ ssize_t iov_iter_get_pages(struct iov_iter *i, if (unlikely(iov_iter_is_pipe(i))) return pipe_get_pages(i, pages, maxsize, maxpages, start); + if (unlikely(iov_iter_is_discard(i))) + return -EFAULT; + iterate_all_kinds(i, maxsize, v, ({ unsigned long addr = (unsigned long)v.iov_base; size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1)); @@ -1274,6 +1308,9 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, if (unlikely(iov_iter_is_pipe(i))) return pipe_get_pages_alloc(i, pages, maxsize, start); + if (unlikely(iov_iter_is_discard(i))) + return -EFAULT; + iterate_all_kinds(i, maxsize, v, ({ unsigned long addr = (unsigned long)v.iov_base; size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1)); @@ -1315,7 +1352,7 @@ size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, __wsum sum, next; size_t off = 0; sum = *csum; - if (unlikely(iov_iter_is_pipe(i))) { + if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { WARN_ON(1); return 0; } @@ -1357,7 +1394,7 @@ bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum, __wsum sum, next; size_t off = 0; sum = *csum; - if (unlikely(iov_iter_is_pipe(i))) { + if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { WARN_ON(1); return false; } @@ -1402,7 +1439,7 @@ size_t csum_and_copy_to_iter(const void *addr, size_t bytes, __wsum *csum, __wsum sum, next; size_t off = 0; sum = *csum; - if (unlikely(iov_iter_is_pipe(i))) { + if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { WARN_ON(1); /* for now */ return 0; } @@ -1444,6 +1481,8 @@ int iov_iter_npages(const struct iov_iter *i, int maxpages) if (!size) return 0; + if (unlikely(iov_iter_is_discard(i))) + return 0; if (unlikely(iov_iter_is_pipe(i))) { struct pipe_inode_info *pipe = i->pipe; @@ -1487,6 +1526,8 @@ const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags) WARN_ON(1); return NULL; } + if (unlikely(iov_iter_is_discard(new))) + return NULL; if (iov_iter_is_bvec(new)) return new->bvec = kmemdup(new->bvec, new->nr_segs * sizeof(struct bio_vec), |